Interbody fusion devices with self-affixing mechanisms

ABSTRACT

Interbody fusion devices including deployable fixation members. The implant may include a spacer, optionally, an end member coupled to the spacer, and one or more fixation members configured to extend into adjacent vertebrae. The fixation members may include screws, nails, shims, tangs, spikes, staples, pins, blades, fins, or the like, and combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of U.S. Ser. No.15/141,122, filed Apr. 28, 2016, which is a continuation application ofU.S. Ser. No. 14/458,687, filed Aug. 13, 2014, now U.S. Pat. No.9,351,847, which claims priority to Provisional Application No.61/868,803 filed Aug. 22, 2013, the entire disclosures of which areincorporated herein by reference in their entireties for all purposes.

FIELD OF THE INVENTION

The present disclosure generally relates to fixation devices forpositioning and immobilizing adjacent vertebral bodies. In particular,the devices may include interbody fusion devices.

BACKGROUND OF THE INVENTION

As people age, the intervertebral discs in the spinal column may startto deteriorate. Subsequently, the intervertebral discs being to loseheight. As a result of the loss of height between vertebral bodies, thenerves exiting from the spinal canal become compressed and pinched,which causes pain among other neurological deficits. One solution is toinsert a spacer in place of the disc to restore the height and topromote fusion between adjacent vertebral bodies to permanently maintainthe height restoration. Additional fixation may also be needed tostabilize the spinal segment. A plate is usually provided, and the platemay be positioned on the anterior portions of the adjacent vertebralbodies. In some cases, the profile of the plate becomes obstructive tothe anatomy. The approach to the spine is also significant in that adirect anterior approach requires navigation or dissection of vascularanatomy.

As a result, there is a need to provide a spacer having fixationelements to attach the spacer directly to adjacent vertebrae, to limitany profile protruding out of the spine column anteriorly, and to avoidproximal anatomy from a direct anterior approach.

SUMMARY OF THE INVENTION

This application relates to interbody fusion devices with self-affixingmechanisms. Each of the interbody fusion devices can be used following adiscectomy to assist in maintaining height between vertebral bodies.While the devices are particularly useful in the anterior spinal column,the devices can be used in different regions of the spine as well.

According to one embodiment, an implant for implantation in a treatedarea of an intervertebral space between vertebral bodies of a spineincludes a spacer, an end member, and at least one fixation member. Thespacer has a superior surface and an inferior surface. The spacer maydefine an opening extending from the superior surface to the inferiorsurface configured to receive bone graft material. The superior surfaceand the inferior surface each have a contact area configured to engageadjacent vertebrae. The end member is coupled to the spacer. The endmember has at least one hole traversing the end member at an angle. Thefixation member is configured to extend through the at least one holetraversing the end member. The fixation member may include a curved shimconfigured to be hammered into adjacent vertebrae. Shims alone may beused to secure the implant or other fixation members may be used incombination with the shim.

The shim may include a spline extending along at least a portion of alongitudinal axis of the shim. The spline may have the greatest heightat a head portion of the shim, which tapers to a smallest heightproximate to a distal most end of the shim. The shim may have a flathead portion. Alternatively, the shim may have a rounded head portionincluding an opening configured to retain an insertion instrument. Inanother embodiment, the shim may be smooth with a substantially conicalshape.

The fixation member may be retained within the end member with ablocking mechanism. The blocking mechanism may include a screw having ahead which covers over and/or rests against a portion of the fixationmember, thereby preventing unintentional backout. Alternatively, theblocking mechanism may include a spring tab configured to block thefixation member once the fixation member is fully inserted into the endmember.

The fixation member may be in a deployable form having a tip configuredto expand after implantation. The deployable fixation member may includean inner portion and an outer sleeve. Once the deployable fixationmember is inserted into bone, the inner portion is capable of beingpulled opposite to the insertion direction to deform and splay the tipof the fixation member open.

According to another embodiment, an implant may include a spacer havinga superior surface and an inferior surface. The superior surface and theinferior surface each have a contact area configured to engage adjacentvertebrae. The spacer defines at least one opening extending from thesuperior surface to the inferior surface. At least one shaft may becoupled to the spacer and extends through the opening in the spacer. Oneor more fins may be operatively attached to the shaft such that rotationof the shaft causes deployment of the one or more fins configured toengage adjacent vertebral bone when deployed.

The fins may be rotated about 90° between retracted and deployedpositions. In one embodiment, the fins may rest on a wall dividing theopening when in the retracted position. In an alternative embodiment,the fins may be sized and shaped such that they are housed within theopening when in the retracted position. The fins may include a pluralityof fins attached to a single shaft. Alternatively, more than one shaftmay be used with one or more fins positioned on each shaft. The fins mayhave a sharpened edge configured to cut through the adjacent vertebralbone. The fins may have straight or hooked shapes, for example.

According to another embodiment, an implant may include a spacer havinga superior surface and an inferior surface. The spacer may include aramped surface positioned on a portion of the superior and/or inferiorsurface. An end member configured to be coupled to the spacer may houseor contain one or more blades. As the end member is attached to thespacer, the one or more blades may engage the ramped surface of thespacer, thereby causing the one or more blades to expand outwardly andengage adjacent vertebrae.

The blades may include two blades attached together via a hinge (e.g., aliving hinge). The blades may have a first, collapsed orientation beforethe end member is attached to the spacer, and a second, expandedorientation where the blades are expanded apart such that an anglebetween the blades is larger than in the collapsed orientation. Theramped surface may be angled such that the ramped surface extends from acentral portion of the spacer and increases in height outward toward thelateral portion of the spacer.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be best understood from the following detaileddescription when read in connection with the accompanying drawing. It isemphasized that, according to common practice, the various features ofthe drawing are not to scale. On the contrary, the dimensions of thevarious features are arbitrarily expanded or reduced for clarity.Included in the drawing are the following figures:

FIG. 1 shows an example of an interbody fusion device implantable in adisc space in accordance with an embodiment of the present application;

FIG. 2 depicts an alternative embodiment of an interbody fusion devicewith self-affixing mechanisms;

FIG. 3 shows an alternative embodiment of an interbody fusion devicewith self-affixing mechanisms;

FIG. 4 depicts an alternative embodiment of an interbody fusion devicewith self-affixing mechanisms;

FIG. 5 shows an alternative embodiment of an interbody fusion devicewith self-affixing mechanisms;

FIG. 6 illustrates a top perspective view of an alternative interbodyfusion device including a spacer body with deployable fins on multipleshafts;

FIG. 7 shows a top perspective view of an alternative interbody fusiondevice including a spacer body with deployable fins on a single shaft;

FIGS. 8A and 8B illustrate top perspective views of an alternativeembodiment of an interbody fusion device having hinged blades;

FIGS. 9A and 9B illustrate an alternative interbody fusion device havingdeployable straight or curved nails;

FIGS. 10A and 10B illustrate a spring tab feature on the embodimentdepicted in FIGS. 9A and 9B;

FIGS. 11A-D provide an alternative interbody fusion device havingdeployable two-piece nails;

FIG. 12A-F show an alternative interbody fusion device having one ormore sets of fins that cut through adjacent bone;

FIGS. 13A and 13B show an alternative interbody fusion device havingdeployable spikes through a rack and pinion design;

FIG. 14 illustrates an alternative interbody fusion device havingdeployable spikes using movable ramps;

FIGS. 15A and 15B show an alternative interbody fusion device having adeformable spike or nail;

FIGS. 16A-C show an alternative embodiment of an interbody fusion devicehaving deployable spikes or nails;

FIGS. 17A and 17B depict an alternative interbody spinal fusion devicethat includes an internal pivoting hook member;

FIGS. 18A-E show an alternative interbody spinal fusion device thatincludes deployable tangs;

FIG. 19 illustrates an interbody fusion device having a mechanism forfacilitating inline operation;

FIGS. 20A and 20B illustrates a universal joint (e.g., a ball joint)that can be built in the head of a bone screw to provide polyaxialadjustability;

FIG. 21 illustrates how deployable nails, fins etc. can be actuated by aworm and/or worm wheel with teeth;

FIG. 22 illustrates an embodiment of an interbody fusion device havingdeployable barb wires through a curved spike hammered in through thespacer body;

FIG. 23 illustrates an alternative interbody fusion device including astraight or curved rack and pinion mechanism; and

FIG. 24 illustrates a keeled connection between a spacer and a vertebralbody.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the disclosure are generally directed to stand-aloneinterbody fusion implants. Specifically, the implants include a spacerbody. The spacer may be combined with an end member. One or morefixation members, such as screws, nails, shims, tangs, spikes, staples,pins, fins, blades, or the like, may be used to secure the device toadjacent vertebrae. The fixation members may also include a combinationof these to provide for optimal ease of insertion and fixation of thedevice.

The embodiments of the disclosure and the various features andadvantageous details thereof are explained more fully with reference tothe non-limiting embodiments and examples that are described and/orillustrated in the accompanying drawings and detailed in the followingdescription. The features of one embodiment may be employed with otherembodiments as the skilled artisan would recognize, even if notexplicitly stated herein. Descriptions of well-known components andprocessing techniques may be omitted so as to not unnecessarily obscurethe embodiments of the disclosure. The examples used herein are intendedmerely to facilitate an understanding of ways in which the disclosuremay be practiced and to further enable those of skill in the art topractice the embodiments of the disclosure. Accordingly, the examplesand embodiments herein should not be construed as limiting the scope ofthe disclosure, which is defined solely by the appended claims andapplicable law. Moreover, it is noted that like reference numeralsrepresent similar parts throughout the several views of the drawings.

As used herein and in the claims, the terms “comprising” and “including”are inclusive or open-ended and do not exclude additional unrecitedelements, compositional components, or method steps. Accordingly, theterms “comprising” and “including” encompass the more restrictive terms“consisting essentially of” and “consisting of.”

Certain embodiments may be used on the cervical, thoracic, lumbar,and/or sacral segments of the spine. The size and mass increase of thevertebrae in the spine from the cervical to the lumbar portions isdirectly related to an increased capacity for supporting larger loads,for example. This increase in load bearing capacity, however, isparalleled by a decrease in flexibility and an increase insusceptibility to strain. When rigid immobilization systems are used inthe lumbar segment, the flexibility is decreased even further beyond thenatural motion restriction of that segment. Replacing the conventionalrigid immobilization systems with certain embodiments disclosed hereinmay generally restore a more natural movement and provide added supportto the strain-susceptible areas.

Referring now to the figures, FIGS. 1-5 depict alternative embodimentsof an interbody fusion device 10 having different types of fixationmembers 28 designed to secure the fusion device 10 to adjacent vertebralbodies. The fixation members 28 may be in the form of one or more screws30, nails or shims 32, or the like.

With reference to FIG. 1, an example of an interbody fusion device 10 inaccordance with one embodiment of the present application is shown,which is implantable in a disc space. The device may comprise a spaceror body portion 12 affixed to an end member 50. The body portion 12 maybe in the form of a spacer or cage having an opening 16 that may serveas a graft opening for receiving graft material. The body portion 12 caninclude a contact area having one or more protrusions 14, for example,in the form of teeth, ridges, or ribs on either or both of its superiorand inferior surfaces 42, 44 to prevent expulsion of the body portion 12between adjacent vertebrae. The body portion 12 can be formed of PEEK(polyether ether ketone), other plastics, titanium, other metal or metalalloys, or other suitable bio-compatible materials known in the art.

The spacer or body portion 12 and the end member 50 may be coupled,removably coupled, connected, or attached together in any suitablemanner known in the art. The body portion 12 and the end member 50 maybe coupled together through appropriate coupling means or fasteners. Forexample, at least a portion of the end member 50 and/or body portion 12may be configured to provide male and female projections and recesses,which act as the mechanical interfaces between the two pieces. The bodyportion 12 and the end member 50 may be assembled together using, aloneor in combination, a friction fit, a dovetail assembly, dowel pins,hooks, staples, screws, adhesives, and the like, or any suitablefasteners known in the art. The end member 50, which can be formed ofmetal, for example, can include one or more openings for receiving oneor more fixation members 28 therethrough. The openings may be angledsuch that the openings extend through the end member 50 at an angledivergent to a horizontal plane. The end member 50 may be contoured anymay include one or more eyebrows, for example, to accommodate the angledtrajectory of the fixation members 28.

The fixation members 28 are configured to extend into a vertebral bodyto provide vertebral fixation. The fixation members 28 may include oneor more components designed to secure the device to adjacent vertebrae.By way of example, the fixation members 28 may be selected from screws,nails, shims, staples, pins, or the like, and combinations thereof. Asshown in FIG. 1, the fixation members 28 can include one or more bonescrews 30 (facing downward in FIG. 1), as well as one or more thinnernails or shims 32 (facing upward in FIG. 1).

The bone screws 30 may include a threaded shaft and a head portion 31.The head portion 31 may be rounded. The screws 30 may include anysuitable screws known in the art including fixed or variable angle ofany suitable size with appropriate thread spacing, thread pitch, headdesign, length, and the like. The screws 30 enter the screw holes in theend member 50 at specified angles to enter each of the adjacentvertebrae at the optimal locations. In particular, the screws 30 may beinserted at an angle for maximum screw purchase into the superior and/orinferior vertebral bodies.

The shims 32 may include a substantially flat or thin piece of materialextending along a longitudinal axis. In some embodiments, the one ormore shims 32 can be curved or angled, while in other embodiments, theone or more shims 32 can be straight. While bone screws 30 providestrength, in some situations, it may desirable to use a thinner nail orshim 32, as such fixation members 28 can be easily inserted. In someembodiments, the bone screw 30 is screwed into bone (e.g., using adriver), while the shim 32 can be hammered into place. The shim 32 mayinclude a head portion 33 which is substantially flattened at itsproximal most end. The flattened head portion 33 may allow for greatercontact area with an insertion instrument, for example, when the shim 32is hammered into place. The shims 32 may include a rounded or pointedtip at the distal most end. The shims 32 may or may not contain anextension or spline 34. If present, the spline 34 may be positioned atany suitable location along the shim 32. For example, the spline 34 mayextend along at least a portion of the longitudinal axis of the shim 32.The spline 34 may also extend to the head portion 33. The spline 34 mayhave the greatest height at the head portion 33 and taper to thesmallest height proximate to the distal most end of the shim 32. A crosspiece may be positioned below the spline 34 and across the head portion33, for example, to further secure the shim 32 to the end member 50and/or stabilize the device 10.

While FIG. 1 shows two bone screws 30 and one shim 32, in otherembodiments, the device can include different numbers, types, andvariations of bone screws 30 and/or shims 32. For example, in someembodiments, the device can be fixed to adjacent vertebrae using onlyshims 32 (e.g., via three or more shims 32). The fixation members 28 cannot only provide a means of fixation between the device 10 andvertebrae, but in some embodiments, can also help lag vertebral bonedown to the spacer body 12.

In some embodiments, the fixation members 28 can be pre-assembled withthe body portion 12 as the body portion 12 is inserted into the discspace. The fixation members 28 would simply need to be deployed into thevertebral bodies once the cage body is in a desired surgical site. Inother embodiments, the fixation members 28 can be inserted into the bodyportion 12 after the body portion 12 is inserted into a disc space.

In addition to having one or more openings for receiving one or morefixation members 28, the end member 50 can include one or more openingsto retain one or more blocking mechanisms 20 to prevent undesirablebackout of the fixation members 28 (e.g., screws 30 or shims 32). Asshown in FIG. 1, the device 10 can include two or more blockingmechanisms 20 (e.g., blocking screws) that prevent backout. In someembodiments, the blocking mechanism 20 can prevent backout of one ormore fixation members 28 (e.g., a bone screw 30 or a nail/shim 32). Inother embodiments, the blocking mechanism 20 can prevent backout of twoor more fixation members 28 (e.g., a bone screw 30 and a nail/shim 32).For example, as shown in FIG. 1, each blocking mechanism 20 serves toblock both the bone screw 30 and the shim 32 from unintended backout. Insome embodiments, the blocking mechanism 20 includes a cut-out portionthat allows for insertion of the fixation member 28 through the endmember 50. Once the fixation member 28 is inserted through the endmember 50, the blocking mechanism 20 can be rotated, such that at leasta portion of the blocking mechanism 20 covers over and/or rests againsta portion of the fixation member 28, thereby preventing unintentionalbackout.

Referring now to FIG. 2, an alternative embodiment of an interbodyfusion device 10 is shown with self-affixing mechanisms. This device 10includes similar features as the device described in FIG. 1, includingbody portion 12, end member 50, one or more fixation members 28, and oneor more blocking mechanisms 20. However, the present device 10 utilizesthree fixation members 28—each comprising a bone screw 30 for maximumfixation. As shown in FIG. 2, two of the bone screws 30 face downwardly,while one of the bone screws 30 faces upwardly.

As shown in FIG. 3, an alternative embodiment of an interbody fusiondevice 10 with self-affixing mechanisms is shown. This device 10includes similar features as the device described in FIG. 1, includingthe body portion 12, the end member 50, one or more fixation members 28,and one or more blocking mechanisms 20. As shown in FIG. 3, the fixationmembers 28 can include one or more bone screws 30 (facing downward inFIG. 3), as well as one or more thinner nails or shims 32 (facing upwardin FIG. 3). However, the present device 10 utilizes a distinct upwardlyfacing nail or shim 32 that is slender and tapered. This shim 32, whichis curved in FIG. 3, advantageously accommodates easy insertion into avertebral body.

Note that in the present embodiment, the shim 32 has a rounded headportion 33, similar to the head portions 31 of the bone screws 30. Therounded head 33 may include an opening, for example, configured toretain an insertion instrument. This is in contrast to the shim 32 inFIG. 1, which does not have a rounded head portion 33, but rather issubstantially flattened at its proximal most end. The rounded head 33 ofthe shim 32 advantageously provides a mechanism for preventingover-insertion of the shim 32 into the device 10. Likewise, however, thesubstantially flattened shim 32 in FIG. 1 can also provide its ownmechanism, such as a tab or particularly shaped feature that preventsover-insertion of the shim 32 in the fusion device 10. Similar to FIG.1, the shims 32 may include a spline 34. The spline 34 may extend alongat least a portion of the longitudinal axis of the shim 32. In thiscase, the spline 34 extends along the entire length of the shim 32. Theshim 32 is also provided with a pointed tip at the distal most end.

FIG. 4 shows an alternative embodiment of an interbody fusion device 10with self-affixing mechanisms in accordance with one embodiment. Thisdevice 10 includes similar features as the device described in FIG. 1,including body portion 12, end member 50, one or more fixation members28, and one or more blocking mechanisms 20. However, in the presentdevice 10, the three fixation devices 28 are each slender, tapered nailsor shims 32. Each of the shims 32 is curved and designed to provide easyaccess into a vertebral body.

FIG. 5 shows an alternative embodiment of an interbody fusion device 10with self-affixing mechanisms in accordance with one embodiment. Thisdevice 10 includes similar features as the device described in FIG. 1,including body portion 12, end member 50, one or more fixation members28, and one or more blocking mechanisms 20. However, in the presentdevice 10, the fixation members 28 comprise three smoothened shims ornails 32 that can be inserted into a vertebral body. These nails 32 maybe substantially conical in shape and do not include splines. The nails32 may or may not include a head portion, and as shown, the nails 32 maybe substantially flattened at its proximal most end. The nails 32 mayinclude a rounded or pointed tip at the distal most end. In someembodiments, the nails 32 can be straight or, as shown in FIG. 5, may becurved, with a minimum of one in the superior direction and one in theinferior direction. The shims or nails 32 can be pressed through thespacer body 12 and retained partially within the spacer body 12. Thenails 32 can be held within the spacer body 32 by a component such as ablocking screw 20. In some embodiments, the shims or nails 32 can beheld in position via a spring tab (see FIGS. 10A and B).

FIG. 6 illustrates a top perspective view of an alternative interbodyfusion device 100 including a spacer body 112 in accordance with someembodiments of the present application. The spacer body 112 may be inthe form of a spacer or cage having one or more openings 116 that mayserve as a graft opening for receiving graft material. As shown, theopening 116 may be divided into two equal parts separated by a centralwall. The spacer body 112 can include a contact area having one or moreprotrusions 114, for example, in the form of teeth, ridges, or ribs oneither or both of its superior and inferior surfaces 142, 144 to preventexpulsion of the spacer body 112 between adjacent vertebrae. In thepresent embodiment, the spacer body 112 is configured to have one ormore ridges on a least a portion of its superior and inferior surfaces142, 144. In addition, it is configured to have one or more fins 152that cut through bone in adjacent vertebrae. The one or more fins 152can be operatively attached to one or more shafts 154. The shaft 154 maybe in the form of a cylinder extending through the opening 116 from aproximal portion to a distal portion of the spacer 112. Rotation of theshaft 154 causes the deployment of the fins 152, which can lodge andengage in adjacent vertebral bone. The fins 152 may have straight orhooked shapes, for example. The fin 152 may have a sharpened edge tofacilitate insertion into the adjacent vertebrae.

As shown in FIG. 6, the device 100 can include two or more shafts 154,each with one or more fins 152 attached thereto. The device 100 may beconfigured such that at least one fin 152 engages a superior vertebraand at least one fin 152 engages an inferior vertebra. As shown, the twoshafts 154 may be offset from one another. The spacer body 112 caninclude one or more actuation openings 156 that provide access to theshafts 154, thereby allowing one or more instruments to rotate andactuate the shafts 154. As shown in FIG. 6, rotation of the shaft 154 ina first direction will cause deployment of the fin 152, for example in asubstantially vertical orientation 152 (not shown), whereas rotation ofthe shaft 154 in a second opposite direction will cause retraction ofthe fin 152, for example, in a substantially horizontal orientation (inthe position shown). In particular, the fin 152 may be rotated about 90°between the retracted and deployed positions. The fins 152 may rest onthe wall dividing the opening 116 when in the retracted position. Thefins 152 may be sized and shaped such that they are unable to enter theopening 116 when actuated.

Each of the shafts 154 can be operated independently from one another.The interbody fusion device 100 in FIG. 6 can advantageously operate onits own, without the addition of a plate or other fixation members.However, in other embodiments, the device 100 in FIG. 6 can also befixed to an end member (as described in other embodiments herein),plate, or the like and can include one or more additional fixationmembers (e.g., bone screws, nails, shims) to provide additional fixationto adjacent vertebral bodies.

FIG. 7 illustrates a top perspective view of an alternative interbodyfusion device 200, which is similar to the device 100 shown in FIG. 6.The device 200 includes a spacer body 212. The spacer body 212 may be inthe form of a spacer or cage having opening 216 that may serve as agraft opening for receiving graft material. In this embodiment, a singleopening 216 is provided in the spacer body 212. Like the fusion device100 in FIG. 6, the present fusion device 200 includes a plurality ofridges on a least a portion of its superior and inferior surfaces 242,244, as well as at least one shaft 254 and at least one fin 252.However, in the present embodiment, the fusion device 200 includes onlyone central shaft 254 with multiple fins 252 extending therefrom (e.g.,three upper and three lower fins 252) attached to the shaft 254. Thefins 252 may be all of the same height and configuration or may bedifferent. The fins 252 may be coaxially aligned with one another on theshaft 254. The shaft 254 may extend centrally through the opening 216from a proximal portion to a distal portion of the spacer 212. The shaft254 may be provided with one or more openings to allow for egress and/oringress of graft material. Rotation of the central shaft 254 causesdeployment of the multiple fins 252 such that three upper fins 252 canengage an upper vertebra, while three lower fins 252 (not shown) canengage a lower vertebra. To rotate the shaft 254, a driver opening 256can be provided to accommodate an actuation or driving instrument.

Rotation of the shaft 254 in a first direction will cause deployment ofthe fins 252, for example, in a substantially vertical orientation(shown in FIG. 7), whereas rotation of the shaft 254 in a secondopposite direction will cause retraction of the fins 252, for example,in a substantially horizontal orientation (not shown). In particular,the fins 252 may be rotated about 90° between the retracted and deployedpositions. The fins 252 may be sized and shaped such that they arehoused within the opening 216 when in the retracted position.

FIGS. 8A and 8B illustrate top perspective views of an alternativeembodiment of an interbody fusion device 300 having hinged blades 352.FIG. 8A shows the device 300 disassembled, while FIG. 8B shows thedevice 300 assembled and configured to be engaged into adjacentvertebrae. The interbody fusion device 300 includes a spacer body 312and an end member 350 configured to be affixed to the spacer body 312.The spacer body 312 may be in the form of a spacer or cage having anopening 316 that may serve as a graft opening for receiving graftmaterial. The spacer body 312 can include one or more protrusions 314,for example, in the form of teeth, ridges, or ribs on either or both ofits superior and inferior surfaces 342, 344 to prevent expulsion of thespacer body 312 between adjacent vertebrae. As shown, the spacer body312 is configured to have a plurality of teeth on a least a portion ofits superior and inferior surfaces 342, 344.

The spacer body 312 includes at least one ramped surface 318. The rampedsurface 318 may be positioned on a portion of the superior and/orinferior surfaces 342, 344 on a proximal portion of the spacer body 312proximate to the end member 350. The ramped surface 318 may include anangled or tapered surface configured to engage a blade 352. The angle ofthe ramped surface 318 may range from about 1-70°, about 5-60°, about10-40°, or about 15-30° relative to a horizontal axis. As shown in FIG.8A, the spacer body 312 may include two ramped surfaces 318 on thesuperior surface 342 and two identical ramped surfaces 318 on theinferior surface 344 (not shown). The ramped surfaces 318 may be angledsuch that they extend from a central portion of the spacer body 312 andincrease in height outward toward the lateral portions of the spacerbody 312.

The spacer body 312 can be removably coupled, attached, or affixed tothe end member 350. The spacer body 312 can be attached to the endmember 350 by a coupling mechanism, friction fit, interference fit, orany other connection means. For example, the spacer body 312 and the endmember 350 may be assembled together using, alone or in combination, adovetail assembly, dowel pins, hooks, staples, screws, adhesives, andthe like, or any suitable fasteners known in the art. The end member 350may include upper and lower surfaces having one or more torsionalstabilizers 370 extending therefrom configured to prevent or minimizetorsional motion of the implant 300 once implanted. The torsionalstabilizers 370 may act as extensions or fins, which may serve as knifeedges to further purchase into the bone of the adjacent vertebrae and/orserve as a stop to abut anterior aspects of the adjacent vertebrae. Thetorsional stabilizer 370 may include a spiked or pointed projection orextension configured to engage adjacent vertebrae. The torsionalstabilizers 370 may be provided at any suitable locations. For example,as shown in FIG. 8B, the torsional stabilizers 370 may be providedproximate to the lateral sides of the end member 350 and are alsoprovided substantially medially on the end member 350 projectingsuperiorly and inferiorly from both the upper and lower surfaces,respectively.

The end member 350 houses one or more blades 352. The blade 352 may havean elongated, relatively thin structure. The blade 352 may besubstantially straight and flat or may be curved. The blade 352 may haveany suitable length and width. For example, the blade 352 may have alength substantially the same as the spacer body 312 and a width that issubstantially the same as the opening 316 in the spacer body 312. Theblade 352 may have a sharpened distal edge to facilitate insertion intothe adjacent vertebrae. The distal edge may also be beveled or chamferedat the corners.

The one or more blades 352 may be attached together via a hinge 358. Forexample, the hinge 358 may be in the form of a cantilevered v-springwith a cross-sectional configuration in the form of a V connecting twoblades 352. The hinge 358 may include a living hinge, barrel hinge,piano hinge, ball and socket type hinge, spring, or other suitable hingeknown in the art. In one embodiment, the hinge 358 may include a livinghinge connecting the blades 352. Living hinges may include one-pieceflexing devices or functional hinges having a flexing zone between theblades 352. The living hinge may be constructed of pliant and/orflexible materials having properties which tolerate the repeated tensionand compression of the opposing surfaces (i.e., the blades 352). The endmember 350 may include one or more openings or windows providingvisualization of the blades 352 and/or hinge 358.

As the spacer body 312 is attached or affixed to the end member 350, theone or more hinged blades 352 engage the ramped surfaces 318 of thespacer 312, thereby causing the blades 352 to spread apart and expandoutwardly. The blades 352 may have a first, collapsed orientation wherethe angle between the blades 352 is small and a second, expandedorientation where the angle between the blades 352 is increased to belarger than in the collapsed orientation. The blades 352 are configuredto engage one or more adjacent vertebral bone members when in theexpanded orientation.

In some embodiments, the body portion 312 is configured to be insertedinto a disc space prior to inserting and attaching the end member 350.After clearing a disc space and performing a total or partialdiscectomy, the body portion 312 can be inserted first into a desirablelocation. Afterwards, the end member 350 with the one or more blades 352connected thereto can be attached to the body portion 312. Duringengagement between the body portion 312 and the end member 350, theblades 352 extend outwardly and into adjacent bone members. In otherembodiments, the body portion 312 can be pre-assembled with the endmember 350 prior to inserting the interbody fusion device 300 in a discspace.

FIGS. 9A and B and FIGS. 10A and B illustrate an alternative interbodyfusion device 400 having deployable straight or curved fixation members428, such as nails. The interbody fusion device 400 may include any ofthe fusion devices described herein. FIG. 9A depicts a top view of aspacer body 412 and an insertion instrument 480 configured for insertingtwo fixation members 428 through the spacer body 412. The insertioninstrument 480 may include a pusher element 482, which may be threaded,for example. As the pusher element 482 is advanced and/or rotated in thedirection of the arrows, the fixation members 428 are advanced into thespacer body 412 and deployed into the adjacent vertebrae. The pusherelement 482 may be ratchet or lever operated, for example. Theinstrument 480 may be able to deploy multiple fixation elements 428simultaneously.

FIG. 9B depicts a side view of the embodiment shown in FIG. 9A where thefixation members 428 (initially depicted as dashed lines) enter thespacer body 412 to be deployed within the superior and inferiorvertebral bodies. For example, the devices 400 may have a minimum of onein the superior direction and one in the inferior direction which arepressed through the spacer body 412 and retained partially within thespacer body 412. The fixation members 428 may be straight or curved andmay include any of the fixation members described herein.

The fixation member 428 may be held within the spacer body 412 with anadditional component, such as a blocking mechanism. The blockingmechanism may include any of the blocking mechanisms described herein,such as a blocking screw. Alternatively, the fixation member 428 couldbe held in position with a spring tab 422. FIG. 10A illustrates a topview of the spacer body 412 having the spring tab 422 in an initialposition before the fixation member 428 is fully inserted, and FIG. 10Billustrates a top view of the same spacer body 412 in a final positionwith the fixation member 428 fully inserted and the spring tab 422engaged to retain the fixation member 428. The spring tab 422 mayinclude a flexible portion that flexes as the fixation member 428 isinserted into the device 400, and blocks the fixation member 428 once itis fully inserted. As shown in FIG. 10B, after insertion, the fixationmember 428 is blocked by the spring tab 422 and is unable to back out ofposition. In addition, the fixation members 428 (e.g., nails) may beprevented from being pushed too far into the vertebral body by a head433, for example, on each nail, or by limits fixed to the deployinginserter instrument 480.

FIGS. 11A-D illustrate an alternative interbody fusion device 500 havingdeployable two-piece fixation members 528, such as nails, that could becurved or straight. The interbody fusion device 500 may include any ofthe fusion devices described herein. FIG. 11A depicts a side view of aspacer body 512 including two-piece fixation member 528 extendingtherethrough and into an adjacent vertebra in an initial, insertionconfiguration. FIG. 11B depicts a side view of the spacer body 512 withthe fixation member 528 in a final, deployed configuration.

In some embodiments, the two-piece fixation member 528 can comprise aninner portion 560 and an outer sleeve 562. The assembled inner and outerparts 560, 562 can be pushed into a vertebral bone together, forexample, as shown in FIG. 11A. Once the assembly is inserted into adesired location into bone, the inner portion 560 is capable of beingpulled back slightly toward the outer sleeve 562 and away from theinsertion direction, as the arrow depicts in FIG. 11B. This actiondeforms and splays the tip 564 of the fixation member 528, therebyadvantageously helping to secure the fixation member 528 and/or theinner portion 560 in the bone. The deployed configuration may help toprevent back out of the fixation member 528. In addition, this methodmay compressively load the graft within the graft window 516 in thespacer body 512. Similarly, FIG. 11C shows an alternative tip 564 forthe fixation member 528 in the initial, insertion configuration, andFIG. 11D shows the tip 564 in the final, deployed configuration. Asabove, the assembled inner portion 560 and outer sleeve 562 can beinserted into a vertebral bone together, and once the assembly is pushedinto a desired location in the bone, the inner portion 560 is pulledopposite to the insertion direction to expand or inflate the tip 564 ofthe fixation member 528.

Similar to the embodiments depicted in FIGS. 6 and 7, FIGS. 12A-F showalternative interbody fusion devices 600 having one or more sets of fins652 that cut through adjacent bone. FIG. 12A shows the device 600 havinga spacer body 612. The spacer body 612 may be in the form of a spacer orcage having opening 616 that may serve as a graft opening for receivinggraft material. As shown, the fusion device 600 may have at least onecentral shaft 654 with one or more sets of fins 652. The fins 652 may beinitially contained within the opening 616 as shown in FIG. 12A. Thefins 652 may be activated by a driver, for example, and the fins 652 mayretain and secure the device 600 once deployed, as shown in FIG. 12B.The one or more sets of fins 652 can be straight or have hooked shapes.FIGS. 12C and D depict a similar set of fins 652 in a deployed statewhere the fins 652 are larger than the graft opening 616. FIGS. 12E andF depict a similar set of fins 652 in a deployed state where the fins652 have a bent or hooked configuration (e.g., L-shaped, J-shaped,C-shaped, or the like). The fins 652 may be all of the same type,height, and configuration or may be different on a given device 600.

Rotation of the central shaft 654 causes deployment of the fins 652 suchthat the fins 652 can engage an upper and/or lower vertebrae. Rotationof the shaft 654 in a first direction will cause deployment of the fins652, for example in a substantially vertical orientation, whereasrotation of the shaft 654 in a second opposite direction will causeretraction of the fins 652, for example, in a substantially horizontalorientation. In particular, the fins 652 may be rotated about 90°between the retracted and deployed positions.

FIGS. 13A and B show an alternative interbody fusion device 700 havingdeployable fixation members 728 through a rack and pinion design.Similar to the other devices described herein, FIG. 13A depicts a topview of a spacer body 712 with a graft opening 716. FIG. 13B depicts aside view of the device 700. One or more fixation members 728 may beconnected or coupled to the spacer body 712 with a rack and pinion 724.The rack and pinion 724 may include circular gear or pinion, whichengages teeth on a linear gear or rack. The rack and pinion 724 mayconvert rotational motion, for example, from a driver, into linearmotion of the fixation members 728. The fixation members 728 may includescrews, nails, shims, spikes, staples, pins, or the like. In anexemplary embodiment, the fixation members 728 are in the form ofdeployable spikes or nails. Alternatively, the interbody fusion device700 can have deployable screws via a worm gear mechanism (see FIG. 21).

FIG. 14 illustrates an alternative interbody fusion device 800 using oneor more movable ramps 826. The ramp 826 may have a translation member836 having one or more ramped surfaces 838 that engage deployablefixation members 828, such as a spikes. As shown in FIG. 14, thetranslation member 836 of the device 800 can include at least two upperramps 838 connected via a bridge, and two lower ramps 838 connected viaa bridge. Each of the ramped surfaces 838 is configured to engage adeployable fixation member 828. As the translation member 836 istranslated (e.g., via a rotatable actuation member) in a firstdirection, the ramped surfaces 838 engage the fixation members 828,thereby deploying them through openings in the upper and lower surfacesof the fusion device 800. Thus, the ramped surfaces 838, when translatedlinearly, cause the fixation members 828 to expand outwardly and engagethe adjacent vertebrae. Although two ramped surfaces 838 are depicted toengage two fixation members 828 on each of the upper and lower surfaces,any suitable number of ramped surfaces 838 and fixation members 828 maybe used.

FIGS. 15A and B show an alternative interbody fusion device 900 havingdeformable fixation members 928, such as a nails or a spikes. Theinterbody fusion device 900 may include any of the fusion devicesdescribed herein. FIG. 15A depicts a side view of a spacer body 912including a first member 962 extending therethrough and into an adjacentvertebrae in an initial, insertion configuration. FIG. 15B depicts aside view of the spacer body 912 with the fixation member 928 in afinal, deployed configuration. The deformable fixation member 928 may becomprised of a two-piece design whereby a first member or outer sleeve962 is first introduced into the vertebral body. A second member orinner portion 960 is then threaded or otherwise pushed through the firstmember 962. The tip of the first member 962 is configured to splay anddeform as shown in FIG. 15B. The deployed configuration may help toprevent back out of the fixation member 928. The fixation members 928may be curved or straight before and/or after being deployed.

FIGS. 16A-C show an alternative embodiment of an interbody fusion device1000 having deployable fixation members 1028, such as spikes or nails.The interbody fusion device 1000 may include any of the fusion devicesdescribed herein. FIG. 16A depicts a side view of a spacer body 1012including fixation members 1028 extending therethrough and into adjacentvertebrae in a deployed configuration. The device 1000 may use athreaded shaft 1054 and two or more keyed parts 1040 that are internallythreaded and move in different directions when the threaded shaft 1054is turned. This motion allows the fixation members 1028, which may beattached to the keyed parts 1040, to deploy in an anterior-superior andanterior-inferior direction as shown (FIG. 16A), as well as in theposterior-superior and posterior-inferior directions (FIG. 16C), ifpreferred.

FIGS. 17A and B show an alternative interbody spinal fusion device 1100that includes an internal pivoting hook member 1128 which is made topivot by an actuation member 1136. The interbody fusion device 1100 mayinclude any of the fusion devices described herein. FIG. 17A depicts aside view of a spacer body 1112 including hook member 1128 retractedwithin the spacer body 1112. FIG. 17B shows a side view of the spacerbody 1112 with the hook member 1128 extending therefrom and into anadjacent vertebra in a deployed configuration. The translation oractuation member 1136 is configured to translate and push the pivotinghook 1028 outward such that it is configured to grip an intervertebralmember. The actuation member 1136 may include a ramped surface orbeveled tip to provide for uniform movement of the hook member 1128. Theactuation member 1136 may be threaded or pushed, and may be locked intoposition to deploy the hook member 1128.

FIGS. 18A-E show an alternative interbody spinal fusion device 1200 thatincludes deployable fixation members 1228, such as tangs. FIG. 18Adepicts a front view of a spacer body 1212 with fixation members 1228configured to extend superiorly and inferiorly. The fixation members1228 may be pressed through the spacer body 1212 (e.g., made of PEEK)and embedded into adjacent vertebral bodies. The fixation members 1228may be tapered such that a distal end of the fixation member 1228 isnarrower than a proximal portion of the fixation member 1228 residingwithin the spacer body 1212. The distal end of the fixation member 1228may have a sharpened edge to facilitate insertion into the adjacentvertebrae. FIG. 18B depicts a side view of the spacer body 1212 with thefixation members 1228 extended therethrough. As shown in FIG. 18C, thefixation members 1228, for example, in the form of tangs, can beprevented from moving out of the spacer body 1212 by one or more springretainers 1222 on the fixation members 1228 and/or on the spacer body1212. The spring retainers 1222 may include a flexible portion thatflexes as the fixation member 1228 is inserted into the device 1200. Asshown in FIG. 18E, the fixation member 1228 could also be locked inposition through a third component, such as a blocking mechanisms 1220(e.g., a blocking screw). The fixation members 1228 may also be lockedin position by locking the proximal ends together as shown in FIG. 18D.The fixation members 1228 may include tangs that are flat or curved. Thefixation members 1228 may be made from metal including hydroxyapatite(HA) coated metal.

To assist in providing easy insertion of the fusion devices above,various instruments are provided. In particular, the instruments helpfacilitate inline operation. In many locations of the spine, such as themost caudal or most cephalad cervical disc spaces (e.g., C5-C6/C6-C7 andC2-C3), it can be hard to insert the fusion devices due to interferenceswith the chin or chest. The same is true for caudal lumbar levels (e.g.,L5-S1), where insertion can be complicated due to interference withtissue. The following descriptions include alternative interbody fusiondevices, some of which facilitate inline operation.

FIG. 19 illustrates an interbody fusion device 1300 having one mechanismfor facilitating inline operation. The fusion device 1300 comprises aspacer body 1312 with an end member 1350. The device 1300 includes acombination of two angled holes 1366 in the spacer body 1312 andcorresponding straight holes 1368 in the end member 1350. A fixationmember, such as a bone screw having a polyaxial head and a shaftattached thereto, is insertable through the end member 1350 and thespacer body 1312. During insertion, the bone screw would be insertedstraight with an appropriate sleeved instrument. As the bone screw isinserted, the sleeve will move back and expose the polyaxial head of thebone screw. As the bone screw is inserted further, the shaft of thescrew hits one of the predrilled angled holes 1366 in the spacer body1312 while the polyaxial head engages the straight hole 1368 in the endmember 1350. In other words, the addition of a polyaxial head on thebone screw allows the shaft to angle through the angled holes 1366. Insome embodiments, the shaft is threaded and can engage an adjacentvertebral body. Using this design, the interbody fusion device 1300 canbe inserted via an inline operation until the shaft of the bone screwangles down the angled hole 1366.

FIGS. 20A and 20B illustrate a universal joint (e.g., a ball joint) thatcan be built in the head 1431 of a bone screw 1430 to provide polyaxialadjustability. In some embodiments, the universal joint can be used withthe embodiment in FIG. 19 to provide a polyaxially adjustable bone screw1430. The screw head 1431 can comprise a spherical trough 1429 with aslot perpendicular to the longitudinal axis of the screw 1430 whichmates with a screw driver 1480, for example, having projectionsconfigured to mate with the trough 1429. This design allows for drivingof the bone screw 1430 into a fusion device at any angle, therebyallowing the shaft of the driver 1480 to remain parallel to a disc spaceif desired.

FIG. 21 illustrates how deployable fixation members, such as nails, finsetc. can be actuated by a worm drive. In particular, the worm drive mayinclude a worm 1546 and/or worm wheel 1548 with teeth at an angle. Theworm 1546 may be in the form of a screw, which meshes with the wormwheel 1548. The worm wheel 1548 may have a wheel-like body with aplurality of teeth positioned along the periphery of the body and whichradially extend outward. The worm wheel 1548 may have teeth machined atan angle configured to interlock with the worm 1546.

FIG. 22 illustrates fixation members, such as spikes 1528, having one ormore deployable barb wires 1572. The barb wires 1572 may be deployedthrough the spike 1528. For example, the spike 1528 may be hammered inthrough the spacer body 1512, and the barbs 1572 may be deployedsimultaneously or after the spike 1528 has been fully implanted. Thebarbs 1572 may extend through a distal portion of the spike 1528. Theends of the barbs 1572 may have a sharp point, and the barbs 1572 may becurved to enhance fixation. The spikes 1528 may be curved or straight,and may include any of the fixation members described herein.

FIG. 23 illustrates an alternative interbody fusion device including astraight or curved rack and pinion mechanism with an inline actuatedpinion 1576 driving a curved or straight rack 1574 into a vertebralbody. The rack 1574 has a longitudinal body and includes a plurality ofteeth on at least one side of the rack 1574. The pinion 1576 has awheel-like body with a plurality of teeth positioned along the peripheryof the body and which radially extend outward. The pinion 1576translates rotation motion (e.g., from a driver) to linear orcurvilinear movement of the rack 1574, thereby causing the rack 1574 tobe deployed into the adjacent vertebral space. In this case, the rack1574 may be acting and functioning as the fixation member.

FIG. 24 illustrates a keeled connection between a spacer and a vertebralbody. The keeled connection may include a plurality of keels 1578, forexample, which are deployable from the superior and/or inferior surfacesof the device. The keels 1578 may be in the form of teeth, ridges, ribs,extensions, fins, or the like. The keels 1578 may include a sharp edgeto further purchase into the bone of the adjacent vertebrae. The keels1578 can be deployed similar to any of the fixation members includingnails, shims, or fins as discussed above.

There are many different features to the present invention and it iscontemplated that these features may be used together or separately.Unless mention was made above to the contrary, it should be noted thatall of the accompanying drawings are not to scale. Thus, the inventionshould not be limited to any particular combination of features or to aparticular application of the invention. Further, it should beunderstood that variations and modifications within the spirit and scopeof the invention might occur to those skilled in the art to which theinvention pertains. Accordingly, all expedient modifications readilyattainable by one versed in the art from the disclosure set forth hereinthat are within the scope and spirit of the present invention are to beincluded as further embodiments of the present invention.

What is claimed is:
 1. A spinal implant comprising: a spacer comprisingan upper surface and a lower surface, wherein the upper surfacecomprises one or more protrusions and the lower surface comprises one ormore protrusions; an end member attached to the spacer, wherein the endmember comprises a first opening and a second opening; a first fixationmember extendable through the first opening, the first fixation memberhaving a head portion and a distal end, wherein the head portion is atleast in part spherical allowing the first fixation member to freelyrotate within the first opening; and a second fixation member extendablethrough the second opening, the second fixation member having a headportion that is at least in part spherical allowing the second fixationmember to freely rotate within the second opening, wherein the firstfixation member is non-threaded and the second fixation member isthreaded, and wherein the first fixation member includes a splineextending from the head portion to the distal end.
 2. The spinal implantof claim 1, wherein the spacer comprises an opening extending from theupper surface to the lower surface.
 3. The spinal implant of claim 1,wherein the spacer is formed of PEEK.
 4. The spinal implant of claim 1,wherein the spacer comprises a female recess and the end membercomprises a male projection insertable into the female recess to attachthe spacer to the end member.
 5. The spinal implant of claim 1, whereina dovetail assembly is formed between the spacer and the end member. 6.The spinal implant of claim 1, wherein the first fixation membercomprises a straight shim.
 7. The spinal implant of claim 1, wherein thefirst fixation member comprises a curved shim.
 8. The spinal implant ofclaim 1, wherein the head portion of the first fixation member includesan opening for receiving an insertion instrument.
 9. The spinal implantof claim 1, wherein the first fixation member continuously tapers fromthe head portion to the distal end.
 10. The spinal implant of claim 1,wherein the first fixation member includes additional splines.
 11. Aspinal implant comprising: a spacer comprising an upper surface and alower surface, wherein the upper surface comprises one or moreprotrusions and the lower surface comprises one or more protrusions; anend member attached to the spacer, wherein the end member comprises afirst opening, a second opening and a third opening; a first fixationmember extendable through the first opening, the first fixation memberhaving a head portion and a distal end, wherein the head portion is atleast in part spherical allowing the first fixation member to freelyrotate within the first opening; a second fixation member extendablethrough the second opening, the second fixation member having a headportion that is at least in part spherical allowing the second fixationmember to freely rotate within the second opening; and a third fixationmember extendable through the third opening, the third fixation memberhaving a head portion that is at least in part spherical allowing thethird fixation member to freely rotate within the third opening, whereinthe first fixation member is non-threaded, wherein the second fixationmember and third fixation member are each threaded, and wherein thefirst fixation member includes at least one spline extending from thehead portion to the distal end.
 12. The spinal implant of claim 11,wherein the first fixation member is straight.
 13. The spinal implant ofclaim 12, wherein the end member is formed of a metallic material. 14.The spinal implant of claim 11, wherein the first fixation member iscurved, while the second fixation member and the third fixation memberare straight.
 15. The spinal implant of claim 11, wherein the firstfixation member extends in an upward angle relative to the spacer andthe second fixation member and the third fixation member each extend ina downward angle relative to the spacer.
 16. The spinal implant of claim11, wherein the spacer is attached to the end member via a dovetailconnection.
 17. The spinal implant of claim 11, further comprising afirst blocking mechanism for blocking the first fixation member and thesecond fixation member from back out.
 18. The spinal implant of claim17, further comprising a second blocking mechanism for blocking thefirst fixation member and the third fixation member from back out. 19.The spinal implant of claim 11, wherein the spacer is formed of PEEK.20. The spinal implant of claim 11, wherein the spacer further comprisesan opening extending from the upper surface to the lower surface.